The majority of the following article applies to SMF 2.0 and higher. Some points may still apply to older versions, but they are not guaranteed to apply in all cases.

Default Spam Prevention

SMF, by default, offers three tools to help you keeping spammers out of your forum:

Account Activation - Administrators can decide to either ask their new members to visit an activation link sent to a newly registered member by email or to put all the newly registered members in the approval queue, and then personally activate only the non-spammer accounts.

The Captcha - Administrators can set a verification code (also known as a 'captcha') that users have to decipher in order to be able to proceed with the registration.

Verification Questions - Administrators can introduce a number of custom questions and answers. Users that are registering have to answer correctly to allow registration.

The level of complexity for a verification code can be set from none (no verification code displayed) to extreme (the letters are extremely distorted and it should be very difficult to decipher for the automated spammers). Be aware that the CAPTCHA has been broken for many years and causes real users more of a headache than the spammers.

There is the box used to configure verification questions. Usually this is the most efficient anti-spam method provided by SMF due to its forum specific nature. There are a few things to note about this method to increase its efficiency:

Automated registration bots are usually quite good at mathematics, so avoid using questions like: what's the result of 2+2?

International audiences may not understand local slang or terminology, so ensure that questions do not alienate potential members and the member base.

The system is not case sensitive, so questions requiring upper case answers will still be accepted if lower case is typed.

Be sure to put in the number of verification questions a user must answer under the configure verification methods category above the verification questions.

From the Administration Center it is possible to set as many questions you wish, and also the number of questions that each user will be asked to answer during the registration. If you configure ten questions and then set to show two in the registration page, SMF will show two random questions from the ten configured each time a new member tries to register. Having a good bank of questions will stop automated bots from building a set of "known answers".

Mods to Prevent Spam

One of the most important SMF features is its ability to be modified, and at the mod site there is an entire category dedicated to Spam Prevention mods.

Some examples of very clever anti-spam mods that have been created by our community are (in alphabetical order):